Re: [PATCH v10 06/26] virt: gunyah: msgq: Add hypercalls to send and receive messages

On 2/23/2023 4:15 PM, Alex Elder wrote:

On 2/14/23 3:23 PM, Elliot Berman wrote:

quoted

Add hypercalls to send and receive messages on a Gunyah message queue.

Signed-off-by: Elliot Berman <redacted>
---
  arch/arm64/gunyah/gunyah_hypercall.c | 32 ++++++++++++++++++++++++++++
  include/linux/gunyah.h               |  7 ++++++
  2 files changed, 39 insertions(+)

diff --git a/arch/arm64/gunyah/gunyah_hypercall.c 

b/arch/arm64/gunyah/gunyah_hypercall.c
index f30d06ee80cf..2ca9ab098ff6 100644

--- a/arch/arm64/gunyah/gunyah_hypercall.c
+++ b/arch/arm64/gunyah/gunyah_hypercall.c

@@ -38,6 +38,8 @@ EXPORT_SYMBOL_GPL(arch_is_gunyah_guest);

                             fn)
  #define GH_HYPERCALL_HYP_IDENTIFY        GH_HYPERCALL(0x8000)
+#define GH_HYPERCALL_MSGQ_SEND            GH_HYPERCALL(0x801B)
+#define GH_HYPERCALL_MSGQ_RECV            GH_HYPERCALL(0x801C)
  /**
   * gh_hypercall_hyp_identify() - Returns build information and 
feature flags

@@ -57,5 +59,35 @@ void gh_hypercall_hyp_identify(struct 

gh_hypercall_hyp_identify_resp *hyp_identi
  }
  EXPORT_SYMBOL_GPL(gh_hypercall_hyp_identify);
+enum gh_error gh_hypercall_msgq_send(u64 capid, size_t size, 
uintptr_t buff, int tx_flags,
+                    bool *ready)
+{
+    struct arm_smccc_res res;
+
+    arm_smccc_1_1_hvc(GH_HYPERCALL_MSGQ_SEND, capid, size, buff, 
tx_flags, 0, &res);
+
+    if (res.a0 == GH_ERROR_OK)
+        *ready = res.a1;
+
+    return res.a0;
+}
+EXPORT_SYMBOL_GPL(gh_hypercall_msgq_send);
+
+enum gh_error gh_hypercall_msgq_recv(u64 capid, uintptr_t buff, 
size_t size, size_t *recv_size,
+                    bool *ready)
+{
+    struct arm_smccc_res res;
+
+    arm_smccc_1_1_hvc(GH_HYPERCALL_MSGQ_RECV, capid, buff, size, 0, 
&res);
+
+    if (res.a0 == GH_ERROR_OK) {
+        *recv_size = res.a1;

Is there any chance the 64-bit size is incompatible
with size_t?  (Too big?)

This is safe because size of messages <= 240.

quoted

+        *ready = res.a2;

         *ready = !!res.a2;

quoted

+    }
+
+    return res.a0;
+}
+EXPORT_SYMBOL_GPL(gh_hypercall_msgq_recv);
+
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Gunyah Hypervisor Hypercalls");

diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index 3fef2854c5e1..cb6df4eec5c2 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h

@@ -112,4 +112,11 @@ struct gh_hypercall_hyp_identify_resp {

  void gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp 
*hyp_identity);
+#define GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH        BIT(0)
+
+enum gh_error gh_hypercall_msgq_send(u64 capid, size_t size, 
uintptr_t buff, int tx_flags,
+                    bool *ready);

Why uintptr_t?  Why not just pass a host pointer (void *)
and do whatever conversion is necessary inside the function?

                     -Alex

quoted

+enum gh_error gh_hypercall_msgq_recv(u64 capid, uintptr_t buff, 
size_t size, size_t *recv_size,
+                    bool *ready);
+
  #endif

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